Nutrient budgeting worksheets

Transcription

1 Nutrient budgeting worksheets Developing a nutrient budget for a dairy farm Based on NutriMatch Budgeting Tool designed by DPI Victoria The following worksheets provide a guide to working through the process of calculating a whole farm nutrient budget. Many advisors will be able to assist farmers with calculating nutrient budgets for the farm as a part of the fertiliser planning process. Often advisors will have spreadsheets or programs that will help crunch the numbers Disclaimer This publication may be of assistance to you but the State of Victoria and its officers do not guarantee that the publication is without flaws of any kind or is wholly appropriate for your particular purpose and therefore disclaims all liability for any error, lose or other consequence which may arise from you relying on any information in this publication While all reasonable efforts have been made to ensure that the information provided in this manual can be relied on to the extent indicted, the authors and editors of the work, Dairy Australia and the Department of Primary Industries Victoria cannot accept responsibility for any inconvenience, material loss or financial loss resulting from the use of this manual. Dairy Australia acknowledges contributions made by other organisations and private individuals. Acceptance of these contributions, however, does not endorse or imply endorsement by the Dairy Australia of any product or services offered by its contributors. ii Developing a nutrient plan for a dairy farm

2 Contents DEVELOPING A NUTRIENT BUDGET FOR A DAIRY FARM... II CONTENTS... III INTRODUCTION... 1 NUTRIENT SOURCES FERTILISER APPLIED NUTRIENTS IMPORTED IN FEED... 4 WORKSHEET 2 - NUTRIENTS IMPORTED IN FEED EFFLUENT APPLIED... 6 WORKSHEET 3 EFFLUENT APPLIED... 7 NUTRIENT USES AND LOSSES NUTRIENTS EXPORTED IN MILK SOLD... 8 WORKSHEET 4 - NUTRIENTS EXPORTED IN MILK SOLD DUNG AND URINE ON LANEWAYS AND YARD... 9 WORKSHEET 5 DUNG AND URINE LOSSES WATER RUNOFF FODDER SOLD OR TAKEN OFF THE MILKING AREA...11 WORKSHEET 7 - FODDER SOLD OR TAKEN OFF THE MILKING AREA NUTRIENTS EXPORTED IN STOCK...12 Example: Nutrient changes on the milking area...12 Example: Nutrient losses from runoff block / heifer rearing area (if replacements reared or beef animals run on runoff block)...12 WORKSHEET 8 - NUTRIENTS EXPORTED IN STOCK...13 TOTAL NUTRIENT REQUIREMENTS MAINTENANCE REQUIREMENTS...14 WORKSHEET 9 - MAINTENANCE CALCULATIONS CAPITAL REQUIREMENTS...16 WORKSHEET 11 - TOTAL NUTRIENT REQUIREMENTS...18 Developing a nutrient plan for a dairy farm iii

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4 Introduction Nutrient budgets are a simple tool to allow farmers to monitor and measure the amount of nutrient coming into and leaving a farm in order to determine if nutrients are in an overall balance, positive or negative state. Just like a balance sheet in accounting, nutrient budgets give us useful information to help us better manage our nutrients and make more informed fertiliser decisions. The following flow diagram helps to explain the important components of a nutrient budget. The numbers in the diagram correspond to following sections and worksheets which explain the components of calculating a nutrient budget for the farm Nutrient budget: Nutrient Sources 1. Fertiliser applied (last season) 2. Nutrients imported in feed 3. Effluent applied Nutrient Uses and Losses 4. Nutrients exported in milk sold 5. Dung and urine on laneways and yard 6. Water runoff 7. Fodder sold or taken off milking area 8. Stock exports Total Nutrient Requirements 9. Maintenance Fertiliser for Soil Factor 10. Capital fertiliser Developing a nutrient plan for a dairy farm 1

5 Nutrient Sources 1. Fertiliser applied Fertilisers are described using the NPKS system which gives you the nutrient analysis of a fertiliser in terms of the percentage of nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) it contains. This allows you to calculate the amount of each nutrient that is applied when a product is spread, or conversely, the amount of a fertiliser product required to apply a particular amount of each nutrient. The worksheet on the following page shows an example of how much of each nutrient is applied when 6.2 tonnes of DAP is spread. Note Worksheet 1 calculates the nutrients spread over the entire milking area. Other areas which received applications of different fertilisers must be looked at separately. 2 Developing a nutrient plan for a dairy farm

6 Worksheet 1 Nutrients applied in fertiliser Nutrients applied to your farm in season.../... Fertiliser Type N % P % K % S % Fertiliser Applied tonnes Conversion to kg. Total fert. applied (kg) Total nutrient applied to farm (kg) Total N Total P Total K Total S Eg x 18 = 1116kg N eg. DAP x Tonnes x 1000 Eg x 20 = 1240kg P Tonnes x Tonnes x 1000 Tonnes x 1000 Eg x 1.6 = 99.2kg S Tonnes x Tonnes x 1000 Tonnes x 1000 Tonnes x 1000 Total nutrient applied to farm (kg) Divide by effective milking area (ha) Nutrient applied (kg/ha) N P K S *Nutrient applications calculated as if applied to the whole farm, not individual paddocks or sections Developing a nutrient plan for a dairy farm 3

7 2. Nutrients imported in feed TABLE 2.1: NUTRIENTS (P, K, S) in milk, grain, fodder and liveweight Nutrient Milk (%kg milk) Grain (kg/tonne DM) Fodder (kg/tonne DM) Liveweight (kg/1000kg livewt) Phosphorus 0.1 3kg 3kg 8kg Potassium kg 17kg 2kg Sulphur kg 2.5kg 2kg Source: Table 25.5, Soil Analysis Interpretation manual, 1999, Peverill, Sparrow & Reuter The shaded columns in Table 2.1 show the nutrient content of grain and fodder which allows us to calculate the nutrients imported onto the farm in bought in feed. For example, it shows that 1 tonne of grain contains 3kg of phosphorus, 4kg potassium and 2.5kg of sulphur. The following page takes us through the steps to calculate the kg of phosphorus, potassium and sulphur imported onto the farm in bought in feed. This information will be used later in calculating the maintenance requirements for the farm. Example: If 200 tonnes of grain and 100 tonnes of silage was fed on a 60ha farm: 1. We need to convert this to tonnes of dry matter. Grain is usually about 90% DM so 200 tonnes of grain wet is only 180 tonnes of grain DM (remember the nutrients are only in the DM, the rest is water) tonnes of grain fed over a milking area of 60ha is 3 tonnes grain/ha. We need to work in common units and so convert all the information to a per hectare basis. 3. Filling in the boxes on the LHS of the following sheet (for concentrates), if we look at phosphorus: 3 tonnes grain/ha X 3 kg P/tonne of grain = 9 kg P/ha has been imported onto the farm in grain. 4. Continue working down this side of the page and work out potassium and sulphur imported in grain. 5. Now we need to convert the 100 tonnes silage to tonnes of dry matter. Let s say it was baled silage at about 50% DM, so 100 tonnes of silage wet is only 50 tonnes of silage DM tonnes of silage fed over a milking area of 60ha is 0.8 tonnes silage/ha. 7. Now fill in the boxes on the RHS of the following sheet (for fodder). 8. The section at the end of the following page is to add the nutrients imported in both grain and fodder together to get a total for nutrients imported onto the farm in feed. Note It is important to consider if the hay and/or silage was fed out in a sacrifice paddock, or certain section of the farm (rather than the whole farm), this needs to be taken into account in calculations. 4 Developing a nutrient plan for a dairy farm

8 Worksheet 2 - Nutrients imported in feed Tonnes of feed must be in Tonnes of Dry Matter (DM). If weight is wet weight or as fed, use the following to convert to dry matter: Guide Wet Weight X Dry matter % 100 = Tonnes of Dry Matter Grain DM = 90% Example. Hay DM = 85% 200 tonnes grain X = 180 tonnes DM Pit silage DM= 33% Baled silage DM = 50% Concentrates (grains, lupins, pellets) * Remember to convert to DM (see above) Grain Tonnes Milking area = Tonne Grain/ha DM = Bought in Fodder (Hay and Silage) (Do not include fodder made on the milking area) Fodder Tonnes Milking area = Tonne Fodder/ha DM = Phosphorus Tonnes Grain/ha X kg P/Tonne = kg P/ha Phosphorus Tonnes Fodder/ha X kg P/Tonne = kg P/ha X 3 = (c1) X 3 = (f1) Potassium Tonnes Grain/ha X kg K/Tonne = kg K/ha Potassium Tonnes Fodder/ha X kg K/Tonne = kg K/ha X 4 = (c2) X 17 = (f2) Sulphur Tonnes Grain/ha X kg S/Tonne = kg S/ha X 2.5 = (c3) Sulphur Tonnes Fodder/ha X kg S/Tonne = kg S/ha X 2.5 = (f3) Total Imports in Grain and *Fodder (Add P,K,S in grain and P,K,S in fodder from above.) Phosphorus Potassium Sulphur kg/ha kg/ha kg/ha kg P Concentrate kg P Fodder kg K Concentrate kg K Fodder kg S Concentrate kg S Fodder (c1) + (f1) (c2) + (f2) (c3) + (f3) (A) (B) (C) = kg P/ha = kg K/ha = kg S/ha (Transfer (A) to Worksheet 9) (Transfer (B) to Worksheet 9) (Transfer (C) to Worksheet 9) *Consider distribution issues. i.e are nutrients spread over the whole farm, feed pad, sacrifice paddock Developing a nutrient plan for a dairy farm 5

9 3. Effluent applied Apart from the potential for off-farm pollution if it is not managed properly, effluent can make a significant difference to your fertiliser budget. The following table contains the results of analysis of farm effluent in Gippsland. Factor Minimum Mean Maximum PH Conductivity Nitrogen (mg/l) Phosphorus (mg/l) Potassium (mg/l) Sulphur (mg/l) Calcium (mg/l) Magnesium (mg/l) Sodium (mg/l) SAR Note: 1 mg/litre = 1 kg/megalitre and 1 megalitre over 1 hectare is equivalent to 100mm of rain or irrigation If 1 megalitre of the mean effluent was spread over 1 hectare the rates of nutrients spread would be 505 kg/ha of nitrogen, 178 kg of phosphorus and 524 kg of potassium etc. A key feature of the effluent analyses is the large range of nutrient and salt concentrations in the samples from different farms. This means that you can t just take the average concentrations and assume that it is good enough to work out application rates. If you did this but happened to have the higher nutrient concentrations, you could be applying 2 to 3 times the rate you expect. Potassium is often the nutrient of highest concentration in effluent and can also lead to problems such as grass tetany if soil potassium levels are allowed to rise beyond recommended levels. Therefore application rates of effluent are usually based on a recommended single application rate of potassium of 60kg/ha or lower depending on soil potassium levels. If a 100 hectare farm produces 3.3 megalitres of effluent over a season and it has the nutrient content of the mean effluent above, the total nutrients in the season s effluent would be: 1667 kg of Nitrogen, 587 kg of Phosphorus, 1729 kg of Potassium and 436 kg of sulphur. If this effluent was applied evenly over the whole farm (which is normally not practical) the application rates of the nutrients would be insignificant in your total nutrient budget. However if the same effluent was applied over a smaller (more practical) area of 29 hectares (to achieve a potassium application rate of 60kg/ha), the application rates would be significant. Fertiliser rates for that area would need to be adjusted to compensate for the nutrients applied in the effluent. A soil test of the area will guide you as to the overall nutrient requirements. See the table below. Nutrient Rate if applied to 100 hectares (kg/ha) Fertiliser equivalent over 100 hectares (kg/ha) Rate if applied to 29 hectares (kg/ha) Fertiliser equivalent over 29 hectares (kg/ha) Nitrogen (N) (urea) (urea) Phosphorus (P) 6 68 (super) (super) Potassium (K) (potash) (potash) Sulphur (S) Developing a nutrient plan for a dairy farm

10 Worksheet 3 Effluent applied Part A: How much per ha and at what rate? What are the concentrations of the nutrients from your effluent analysis? (mg/l is the same ratio as kg/megalitre (ML)) Nitrogen (N) kg/ml (mg/l) Potassium (K) kg/ml (mg/l) Phosphorus (P) kg/ml (mg/l) Sulphur (S) kg/ml (mg/l) Potassium as the limiting factor Desired potassium application rate kg/ha (i) (recommended maximum = 60kg/ha, less if soil test levels of potassium are adequate) Potassium (from analysis) = ha (ii) kg/ml (i) (from above) To apply desired application rate of potassium use a rate of 1 megalitre of effluent per (ii) ha s To convert from ML/ha to an application depth (mm) simply divide 100 by the area (ha). If 1 ML is applied to 1ha it is applied at a depth of 100mm. Therefore 1ML/ha = 100mm application depth. 100 mm (ii) = mm (iii) To apply desired application rate of potassium use a depth of (iii) mm Part B: What nutrients are being applied? Nitrogen (from analysis) = kg/ha N kg/ml (ii) (from above) Phosphorus (from analysis) kg/ml (ii) (from above) Potassium (i) = kg/ha K (E) Sulphur (from analysis) The figures for P, K and S will be used in calculating the maintenance requirements for the part of the farm where the effluent was applied. Nutrients in effluent applied kg P/ha (D) kg K/ha (E) kg S/ha (F) (Transfer (D), (E) and (F) to Worksheet 9) Developing a nutrient plan for a dairy farm 7

11 Nutrient Uses and Losses 4. Nutrients exported in milk sold This page takes us through the steps to calculate the kg of phosphorus, potassium and sulphur exported from the farm in milk sold. This information will be used later in calculating the maintenance requirements for the farm. TABLE 4.1 NUTRIENTS (P, K, S) in milk, grain, fodder and liveweight Nutrient Milk (%kg milk) Grain (kg/tonne DM) Fodder (kg/tonne DM) Liveweight (kg/1000kg livewt) Phosphorus 0.1 3kg 3kg 8kg Potassium kg 17kg 2kg Sulphur kg 2.5kg 2kg Source: Table 25.5, Soil Analysis Interpretation manual, 1999, Peverill, Sparrow & Reuter The table above shows that every litre of milk produced contains 0.1% phosphorus, 0.14% potassium and 0.03% sulphur. Example: If a farm produced 1,100,000 litres of milk from a milking area of 60ha 1. Again, we need to work in common units and so 1,100,000 litres of milk = 1,100,000 kg of milk and we need to convert the total milk produced on the farm to kg milk/ha. This is done by dividing the total kg milk by the effective milking area: 1,100,000 kg milk divided by 60ha = 18,333 kg milk/ha. 2. Filling in the boxes as we work through the following sheet, if we look at phosphorus: 18,333 kg milk/ha X 0.1 (P% in milk) divided by 100 = 18.3 kg P/ha has been exported from the farm in milk sold. 3. Continue working down this page and work out potassium and sulphur exported in milk. Worksheet 4 - Nutrients exported in milk sold Milk kg/hectare Total kg Milk Effective Milking Area = kg Milk/ha Phosphorus ha = Total exports in milk kg Milk/ha X P% in Milk 100 = kg P exported/ha Potassium X = (G) Transfer to Worksheet 9 kg Milk/ha X K% in Milk 100 = kg K exported/ha Sulphur X = (H) Transfer to Worksheet 9 kg Milk/ha X S% in Milk 100 = kg S exported/ha X = (I) Transfer to Worksheet 9 8 Developing a nutrient plan for a dairy farm

12 5. Dung and urine on laneways and yard This is a new calculation from the Phosphorus for Dairy Farms project, to include when working out the maintenance fertiliser requirements for your farm. It makes an allowance for the nutrients lost in dung and urine while the cows are walking up the laneways and standing in the dairy yard (as these nutrients are not being redistributed around the farm as dung and urine in the paddocks are). You need to know the stocking rate of your farm, which is calculated by dividing the number of cows you milk by the milking area of your farm. For example, 200 cows on a 60ha farm is a stocking rate of 3.3 cows/ha. The formulas to work out the loss of phosphorus, potassium and sulphur from dung and urine in the laneways and dairy yard are below and also on the maintenance calculations worksheet. Worksheet 5 Dung and urine losses Phosphorus: The formula is 0.8kg P x stocking rate (SR). The 0.8kg phosphorus is the figure the researchers have come up with as an estimate of losses, and you need to multiply it by your stocking rate because of course the more cows you run per hectare, the greater the loss of phosphorus in laneways and the dairy yard. Example: For our calculated SR of 3.3 cows/ha, the estimated loss of phosphorus would be 0.8kg P x 3.3 SR = 2.6 kg P/ha (this is already per hectare as your SR is cows/ha). 0.8 kg P x Stocking Rate (cows/ha) = kg P lost /ha 0.8 x = (J) Transfer to WS 9 Potassium: The formula is 5-8kg K x SR. There is a decision you need to make for this calculation based on how long your cows spend in the laneways and dairy yard. If the cows don t have to walk too far and are not waiting around in the yard for long, then use 5kg K in your calculation. The other extreme would be cows walking very long distances and standing in the yard for long periods of time each milking. In this case use 8kg K in your calculation. If the time your cows spend in the laneways and yard is somewhere in-between these two extremes, then use 6 or 7kg K in your calculation. Example: Let s say your cows have up to 1km to walk in the laneways and wait in the yard, on average, up to 1 hour, so I ll use 6kg K in the calculation 6kg K x 3.3 SR = 19.8 kg K/ha (you can see the K losses are much higher than P) 5 to 8 kg K x Stocking Rate (cows/ha) = kg K lost /ha x = (K) Transfer to WS 9 Sulphur: The formula is 0.8kg S x SR Example: For our calculated SR of 3.3 cows/ha, the estimated loss of sulphur would be 0.8kg S x 3.3 SR = 2.6 kg S/ha (this is the same as P losses) 0.8 kg S x Stocking Rate (cows/ha) = kg S lost /ha 0.8 x = (L) Transfer to WS 9 Developing a nutrient plan for a dairy farm 9

13 Phosphorus lost in runofff 6. Water runoff Keep phosphorus on the farm - Phosphorus fertiliser does not need to be washed in Even in dry conditions (eg.summer), phosphorus fertiliser granules absorb moisture from the soil and air. As water moves in, phosphorus moves out of the granule and into the soil, where it locks onto soil particles. Within a week most of the phosphorus has moved into the soil, leaving the granule carrier material and a bit of insoluble phosphorus on the soil surface. Phosphorus moves into the soil Soil Processes Moisture in Air Fertiliser P Soil Moisture Aim for 7 days (a minimum of 4 days) between fertiliser application and runoff Aim to apply fertiliser 7 days (at least 4 days) before your next irrigation Watch the seven-day forecasts and only apply fertiliser if storms that may produce runoff are not predicted in the next week. Phosphorus lost in runoff related to fertiliser application and subsequent runoff event Days from fertilising You control these nutrient exports Currently we can't control these exports Key messages from graph Large amounts of phosphorus can be lost if a runoff event occurs the same day as fertiliser application. The more time between fertiliser application and the next runoff event the smaller the amount of phosphorus lost The amount of phosphorus lost in runoff from fertiliser application is halved by day 4 and is 1 quarter the amount by day 7. The timing of application can control phosphorus losses from fertiliser application. Key factors in keeping nutrients on the farm Whether your runoff of phosphorus and other nutrients is low or high depends on the following factors: total water use per season the percentage of irrigation water coming onto your bays that runs off the farm. soil type and rainfall characteristics which influence the percentage of rainfall which runs off the farm if you separate fertiliser application from the next irrigation or rainfall runoff event. 10 Developing a nutrient plan for a dairy farm

14 7. Fodder sold or taken off the milking area When fodder that is made on one area is sold or taken away and fed on another area, a significant quantity of nutrients are exported in the fodder. This section is for fodder grown and harvested on the home farm and sold or taken off the farm. This section can also be used to calculate the nutrient removal on an area of the farm where fodder is frequently harvested, or for a runoff block that is frequently cut for hay or silage and the fodder is brought to the home farm. Worksheet 7 - Fodder sold or taken off the milking area (Hay and Silage) (Do not include fodder made and fed back on the milking area) Fodder Tonnes Sold/Off Milking area = Tonne Fodder/ha = Phosphorus Tonnes Fodder/ha X kg P/Tonne = kg P/ha X 3 = (M) Transfer to Worksheet 9 Potassium Tonnes Fodder/ha X kg K/Tonne = kg K/ha X 17 = (N) Transfer to Worksheet 9 Sulphur Tonnes Fodder/ha X kg S/Tonne = kg S/ha X 2.5 = (O) Transfer to Worksheet 9 Developing a nutrient plan for a dairy farm 11

15 8. Nutrients exported in stock TABLE 8.1: NUTRIENTS (P, K, S) in milk, grain, fodder and liveweight Nutrient Milk (%kg milk) Grain (kg/tonne DM) Fodder (kg/tonne DM) Liveweight (kg/1000kg livewt) Phosphorus 0.1 3kg 3kg 8kg Potassium kg 17kg 2kg Sulphur kg 2.5kg 2kg Source: Table 25.5, Soil Analysis Interpretation manual, 1999, Peverill, Sparrow & Reuter Nutrients are removed from the soil & plant & cow nutrient cycle when they are used in building bodies of growing livestock. For each tonne of liveweight gained, 8 kg of phosphorus, 2 kg potassium and 2 kg of sulphur are used. Example: Nutrient changes on the milking area In a dairy system, say a 200 Friesian cow self-replacing herd, rearing 50 heifer replacements each year. (assuming 50 replacements come on at 500kgLW and 50 culls leave area at 550 kglw). As you will see, in this example the nutrient changes are very low. If you are in a similar situation, nutrient changes due to stock transfers are probably not worth worrying about in your farm nutrient budget. Total Liveweight gain / loss (tonnes) LW kg/hd Number of head Kg Live Weight Gain Replacements in (Fresian) ,000 Culls out (Fresian) (-) 27,500 Total kg LW Lost (-) 2,500 Total tonnes LW Lost (-) 2.5 Nutrient Phosphorus Potassium Sulphur Kg of nutrient /tonne of Liveweight Gain* 8 kg 2 kg 2 kg kg nutrient total (B) x LW lost (2.5) kg nutrient per ha kg nutrient total Area (100 ha) Example: Nutrient losses from runoff block / heifer rearing area (if replacements reared or beef animals run on runoff block) In any one year the farm will be carrying 50 rising 1 year olds and 50 rising 2 year olds. As a Johnes Disease control measure, all young stock are reared on a runoff block or a separate 25 ha of the farm. If you are doing a nutrient budget for the runoff block, don t forget any nutrients brought in or sent off with feed. Liveweight gain / loss (tonnes) Initial LW kg/hd Final LW kg/hd Change in LW kg/hd Number of head Kg Live Weight Gain Rising 1 Year Olds (Fresian) ,000 Rising 2 Year Olds (Fresian) Total kg LW Gain 20,000 Total tonnes LW Gain 20 Nutrient Phosphorus Potassium Sulphur kg/tonne LW Gain 8 kg 2 kg 2 kg kg nutrient total kg/tonne LW Gain t x LW gain kg nutrient per ha kg nutrient total Area 25 ha Developing a nutrient plan for a dairy farm

16 Worksheet 8 - Nutrients exported in stock Rising One Year Olds LW as 1 Year Old LW at Weaning = kg LW gain 1YOs = (a) kg LW gain 1YOs (a) X Number 1 YOs = total kg LW gain 1YOs X = (b) Rising 2 Year Olds LW as 2 Years Old LW 1 Years Old = kg LW gain 2YOs = (c) kg LW gain 2YOs (c) X Number 2 YOs = total kg LW gain 2YOs X = (d) Total Live Weight Gain Heifers Total kg LW gain 1YOs (b) + Total kg LW gain 2YOs (d) = Total kg LW Gain Heifers + = (e) Total Live Weight Gain t/ha Total LW Gain Heifers (e) 1000kg Heifer Area ha = t LW Gain/ha 1000kg = (f) Total nutrient exports in liveweight Phosphorus t LW Gain/ha (f) X kg P per t LW gain = kg P exported/ha X 8 = (P) Transfer to WS 9 Potassium t LW Gain/ha (f) X kg K per t LW gain = kg K exported/ha X 2 = (Q) Transfer to WS 9 Sulphur t LW Gain/ha (f) X kg S per t LW gain = kg S exported/ha X 2 = (R) Transfer to WS 9 Developing a nutrient plan for a dairy farm 13

17 Total nutrient requirements 9. Maintenance requirements The maintenance soil factor is the number of kg of nutrient per ha to be applied annually to maintain the current soil nutrient status. This accounts for losses within the soil structure in the case of phosphorus, and leaching from the soil in the case of potassium and sulphur. Soils with high P holding capacity will remove P from the plant available pool more quickly, and will have a higher soils maintenance factor. Soil Factors - MAINTENANCE The following soil factor (kg/ha) is to account for the nutrients applied that are held by the soil in order to satisfy its requirements over 12 months. TABLE 9.1: Approximate amount of potassium and sulphur (kg/ha/yr) required to satisfy the soil retention factor over a range of soil types Soil type PBI Amount K to maintain present soil K levels Amount S to maintain present soil S levels Sand Sandy loam Sandy clay loam Silty clay loam Clay loam Clay Volcanic clay Peat > Source: Adapted from Accounting for Nutrients Fertiliser Budgeting tool ( and Cameron Gourley, DPI, Ellinbank (pers. Com.) Note: Due to the relatively high mobility of potassium and sulphur combined with minimal research on these 2 elements the potassium and sulphur figures in the above table are estimates based on current research data. Monitoring soil tests over time will be important to validate potassium and sulphur fertiliser applications levels. TABLE 9.2: Approximate amount of phosphorus required (kg/ha/yr) to satisfy the soil retention factor for a range of PBI values and Olsen P levels PBI Value Current Olsen P Level (mg/kg) 2 to 4 5 to 7 8 to to to to to 35 0 to to to to to Over Source: Adapted from Burkitt et al. (2002). Note. Table 9.2 is based on latest research results and is still being reviewed. As always, monitoring soil tests over time will be important to validate phosphorus fertiliser applications levels. TABLE 9.3: Approximate amount of phosphorus required (kg/ha/yr) to satisfy the soil retention factor for a range of PBI values and Colwell P levels PBI Value Current Colwell P Level (mg/kg) 10 to to to to to to 115 > to to to to to Over Source: Adapted from Accounting for Nutrients Fertiliser Budgeting tool ( 14 Developing a nutrient plan for a dairy farm

18 Worksheet 9 - Maintenance Calculations Paddock or area name Soil Type Phosphorus 1. Milk Worksheet 4 (G) 1. Nuts Imported Worksheet 2 (A) + In feed 2. Lanes & dairy Worksheet 5 (J) Nutrients in Worksheet 3 (D) - only 3. Runoff See sheet 6 applied effluent applies to effluent + irrigation paddocks 4. Fodder & Stock Worksheets 7(M)+8(P) sold Add 1 to 4 From table 9.2or 9.3 Add 1 & = (S) Total Nutrients P soil Total Nutrients Maintenance P Out Requirement Imported (kg/ha) (kg/ha) (kg/ha) (kg/ha) Potassium 1. Milk Worksheet 4 (H) 1. Nuts Imported Worksheet 2 (B) + In feed 2. Lanes & dairy Worksheet 5 (K) Nutrients in Worksheet 3 (E) - only 3. Fodder & Stock Worksheets 7(N)+8(Q) applied effluent applies to effluent sold irrigation paddocks Add 1 to 3 Add 1 & 2 From table = (T) Total Nutrients K soil Total Nutrients Maintenance K Out Requirement Imported (kg/ha) (kg/ha) (kg/ha) (kg/ha) Sulphur 1. Milk Worksheet 4 (I) 1. Nuts Imported Worksheet 2 (C) + In feed 2. Lanes & dairy Worksheet 5 (L) Nutrients in Worksheet 3 (F) - only 3. Fodder & Stock Worksheets 7(O)+8(R) applied effluent applies to effluent sold irrigation paddocks Add 1 to 3 From table 9.1 Add 1 & = (U) Total Nutrients S soil Total Nutrients Maintenance S Out Requirement Imported (kg/ha) (kg/ha) (kg/ha) (kg/ha) Transfer (S), (T) and (U) to worksheet 11 Developing a nutrient plan for a dairy farm 15

19 10. Capital Requirements The capital fertiliser application is the portion of the total fertiliser application that is over and above maintenance requirements, and will result in an increase in the soil nutrient status. Determining the requirement for capital application can only be done with consideration of a recent soil test. Capital Targets Pasture growth is limited to the most limiting growth factor, water, sunlight warmth, and macronutrients phosphorus, sulphur, potassium, etc. Target soil fertility levels for the macronutrients are therefore set for the most limiting nutrient. There is no point continuing to increase say the sulphur level if the potassium level is too low, or conversely continuing to increase the potassium level if the phosphorus level is low. Guidelines for the soil test levels of P, K and S, for Low, Marginal, Moderate and High soil fertility status can be found in Chapter 8 Capital Soil Factor The Capital Soil Factor (shown below) gives an indication of the number of kg of nutrient per ha, above maintenance, required to lift the soil test level by one unit. Capital soil factor is dependent on soil type, the higher the clay content the higher the capital soil factor. Soil Factors - CAPITAL The following soil factors are the amount of nutrient (kg/ha) above maintenance required to increase the soil fertility by 1 unit. Table 10.1 The approximate amount of capital P (kg/ha) required to raise soil Olsen or Colwell P by one unit (1 mg/kg) based on the PBI Soil Type PBI Amount of P to raise Olsen P by 1 unit (kg/ha) Amount of P to raise Colwell P by 1 unit (kg/ha) Sand 0 to Sandy loam 51 to Sandy clay loam 101 to Silty clay loam 101 to Clay loam 301 to Clay 401 to Volcanic clay 501 to Peat Over Source: Adapted from Accounting for Nutrients Fertiliser Budgeting tool ( Table 10.2: The estimated amount of capital potassium (kg/ha) required to raise the soil level by one unit (1 mg/kg) Soil Type PBI Potassium (kg K/Unit of K) Sand Sandy Loam Sandy clay loam Silty clay loam Clay Loam Clay Volcanic clay Peat > Source: Adapted from Accounting for Nutrients Fertiliser Budgeting tool ( and Cameron Gourley, DPI, Ellinbank (pers. Com.) 16 Developing a nutrient plan for a dairy farm

20 Worksheet 10 - Capital Calculations Capital P Target Current = Olsen P Units Olsen P Olsen P to increase # Olsen P Units Kg P/Ha to lift Capital P required ## to increase X Olsen P by 1 unit = (above maintenance) from above # from table 10.1 X = Capital P required Number of years = Capital P Required/ha to reach target (per year) from above ## = Kg P /ha (V) Capital K Target Current = K Units K level K level to increase # K Units Kg K/Ha to lift Capital K required ## to increase X K level by 1 unit = (above maintenance) from above # from table 10.2 X = Capital K required Number of years = Capital K Required/ha to reach target (per year) from above ## = Kg K/ha (W) Capital Current S level (from soil test) S From this soil test level a corresponding amount of sulphur to apply can be found in the box below S Result Interpretation Level S Test level S Required/ha Very High >20 0 Adequate Moderate kg S/ha Marginal kg S/ha Low <4 30kg S/ha Source: and Cameron Gourley, DPI, Ellinbank (pers. Com.) Capital S Required/ha (per year) Kg S/ha (X) Transfer (V), (W) and (X) to worksheet 11 Developing a nutrient plan for a dairy farm 17

21 Worksheet 11 - Total Nutrient Requirements Total Phosphorus Required Maintenance + Capital = Total kg P / ha/ yr (S) + ( (V) Please Note: Calculate the rate of fertiliser to apply based on the nutrient application rate. Consider areas, which require MORE/LESS nutrient, egs. hay/silage, sacrifice paddock, newly sown. Total Potassium Required Maintenance + Capital = Total kg K / ha/ yr (T) + (W) = Please Note: Calculate the rate of fertiliser to apply based on the nutrient application rate. Maximum single application of K suggested is 60 kg K/ha. Maximum annual application of suggested K is 120 kg K/ha. Potassium is reasonably mobile in the soil and may be leached, especially in a very wet season and in sandy soils. It is preferable to apply K after silage/hay is removed to avoid fodder having a high concentration of K. May generate a grass tetany problem next autumn if feeding this high K fodder to springers/fresh cows. Total Sulphur Required Maintenance + Capital = Total kg S / ha/ yr (U) (X) + = Please Note: Calculate the rate of fertiliser to apply based on the nutrient application rate. Sulphur is very mobile and easily leached, especially in a very wet season. If nitrogen is being applied in cold wet conditions (late winter/earl spring), consider applying a product containing sulphur. Reminder: It is important to monitor your soil fertility regularly with soil tests 18 Developing a nutrient plan for a dairy farm